Liquidambar styraciflua tree to about 30 m; lives about 150 years; bark gray, fissured, twigs often with corky wings, stubby spur branches with crowded leaf scars or leaves; taprooted on well drained sites; may be vesicular-arbuscular mycorrhizal (Glomus mosseae).
Leaves alternate, star-shaped, about 12-20 cm wide, 5-7 lobed (Petrides 1988), lobes finely toothed. Leaves expand early to mid-May; winter plant leafless 167 days (Britton 1874); may reproduce clonally from root sprouts (in GA), especially if disturbed.
Flowers monoecious, male flowers tiny, inflorescences 5-10 cm long, female flowers green, in heads, blooms April-May, wind pollinated.
Fruit multiple, beaked capsules, forming spiky balls, about 3-4 cm wide. Sept.-Oct.; seeds 1-2 per capsule, small, winged; wind dispersed from open beaks in fruit during fall and winter, fruit remains on tree late into winter; seeds eaten by birds and small mammals.
Wetland status: FAC.
Frequency in New York City: Very common.
Habitat: Uplands to swamp forests, often in almost pure, even-aged stands. NYC is northern edge of range. Moderately flood tolerant, especially when dormant (Sinclair et al. 1987). Tolerates flooding up to 75% of growing season (Hightshoe 1988), (this difference in flood tolerance may apply to southern versus northern populations (not seen growing in standing water near NYC). Prefers soil pH 4.5-7 (USDA, NRCS 2010). In NYC, found on soils with pH 4.4-5.6 (Gargiullo unpublished data) (also seen growing in concrete rubble). Tolerant of compaction. Moderately tolerant of salt. Shade intolerant pioneer of open areas, index 2-4 (Hightshoe 1988).
Notes: Dense, even-age stands appear to self-thin over time; shaded branches die back. Subject to fire damage that opens trees to fungal infections. Trees weakened by drought or injury can be infected by Botryosphaeria dothidea (Ascomycotina), which causes cankers and die back of stressed tissues. Sometimes infected by the butt rot Ganoderma applanatum (Basidiomycotina), the fruiting body (basidiocarp) of this is the large, hard bracket fungus, known as the artist’s fungus, as the white underside turns brown when scratched. Infection weakens the base of the tree and leads to wind throw with breakage near the tree base. Leaves attacked by forest tent caterpillar, Malacosoma disstria and the larva of the luna moth (Actias luna, Saturniidae). Sweetgum is the primary host of the scale insect Diaspidiotus liquidambaris, (Homoptera, an armored scale, Diaspididae) which causes yellow spots on the upper leaf surface especially along the veins, eventually the scale forms small, warty galls on the leaf upper surface. The second generation of the season feeds on leaf buds and twigs, where they overwinter. (Burns and Honkala 1990; Sinclair et al. 1987; Agrios 1988; Johnson and Lyon 1991; Borror and White 1970; McKnight and McKnight 1987).